The present invention generally relates to improvements in computer systems and application software for the development, validation and maintenance of addressing systems and the automated routing of emergency telephone calls from both fixed land sites and mobile wireless locations.
The number 9-1-1 is a three digit telephone number that has been designated as the universal emergency number for public use to request emergency assistance. The code 9-1-1 was chosen because it is brief, easily remembered and can be dialed quickly. With reference to FIG. 1, basic 9-1-1 system 10, comprises a telephone 12, a telephone company (TelCo) central office 14 in telecommunication with the phone over a fixed wireline telephone network 16, and a public service answering point (PSAP) 18 in telecommunication with the central office. Depending on the area of service, typically a county or state, there may be one or more PSAPs. It is the function of PSAP 18 to transfer the call to the proper law enforcement, fire protection, emergency medical service or agency, etc. (collectively, xe2x80x9cemergency service providersxe2x80x9d) responsible for responding to the emergency. In system 10, all 9-1-1 calls originating from telephone 12 are directed to a particular PSAP 18 through central office 14, depending on the exchange of the calling party number (CPN). In system 10, a call-taker (not shown) in PSAP 18 must determine the location and type of the emergency and transfer the call to the proper one of a plurality of emergency service providers ESP1, ESP2, . . . ESPn that should respond to the call.
An enhanced 9-1-1 (E-911) system has evolved from the Basic 9-1-1 system by providing an automated system for selectively routing 9-1-1 calls originating from telephone equipment at fixed address locations to the proper PSAP. With reference now to FIG. 2, E-911 system 30 comprises telephone 12 located at a fixed location, and central office 14 in telecommunication with telephone 12. The latter has an associated telephone number TN2 and a calling party number CPN. System 30 further includes a regional 9-1-1 telephone switch 32 in telecommunication with central office 14, and a selective routing database (SRDB) 34 comprising a database of telephone numbers, wherein the SRDB and the switch are in electronic communication. Switch 32 is an automated switching device that searches a database of telephone numbers in SRDB 34 for a match with the particular CPN. System 30 determines the primary PSAP, i.e., the PSAP that should receive emergency calls from the address of the subscriber of the CPN from SRDB 34. PSAP 18 includes a 9-1-1 sub-system (not shown) for querying an external database, as described in greater detail below.
With continuing reference to FIG. 2, system 30 further includes a master street address guide (MSAG) 42, which is a listing of all streets and house numbers ranges within a 9-1-1 service area. The streets and address ranges are assigned selective routing codes, or emergency service numbers (ESNs), to enable proper routing of 9-1-1 calls. Thus, the MSAG is a summary database of valid address ranges, with the corresponding ESN for each range. The ESN is a unique number assigned to each combination of PSAP, law, fire and emergency service (EMS) provider and, in some areas, the community name or other delineated zone. System 30 further includes an automatic location identifier Data Base Management System (ALI/DBMS) 48 of CPN, subscriber name and address information and the law, fire and EMS emergency service providers for that location. ALI/DBMS 48 is in electronic communication with PSAP 18, MSAG 42 and SRDB 34. The emergency service providers ESPn have been automatically assigned from the address ranges in MSAG 42. In system 30, upon having the call routed to the appropriate PSAP, this PSAP (e.g., PSAP 18) queries ALI/DMBS 48 to determine the name and address of the CPN subscriber and predetermined emergency service providers ESPn. This information is then displayed on a call-takers screen.
Routing of calls from telephone 12 to primary PSAP 18 is accomplished by finding the address of the calling party, as obtained from TelCo records in MSAG 42. With continuing reference to FIG. 2 and system 30, a 9-1-1 call from telephone 12 at a specific street address location is received at TelCo central office 14 and is transferred to regional 9-1-1 switch 32. Switch 32 then searches a database of telephone numbers in SRDB 34 for a match with the CPN. SRDB 34 returns to switch 32 the telephone number TN of PSAP 18, i.e., the PSAP that should receive emergency calls from the address of the subscriber of the CPN. Switch 32 then uses this TN number to transfer the 9-1-1 call to the designated PSAP. The appropriate PSAP telephone number for each CPN has been pre-loaded into SRDB 34 by comparing the addresses of all TelCo subscribers with MSAG 42 and storing or updating SRDB 34 with the correct PSAP data. The database comparisons are performed on a daily basis within ALI/DMBS 48. Upon transfer to PSAP 18, the PSAP 9-1-1 sub-system queries ALI/DBMS 48 with the CPN and retrieves information (e.g., name, address, etc.) of emergency service providers ESPn that serve that address location.
Implementation of an E-911 system requires valid locatable addressing to perform properly. Many rural areas do not have city-style addressing and must change United States Postal Service (USPS) rural route and box numbers into valid locatable addresses. All areas, regardless of addressing status, must insure that every address is unique. That is, duplicate road names and/or addresses in the same municipality must be eliminated. If an area is to be re-addressed, the municipality must establish a standard distance between whole numbered addresses and establish one side of the road for odd numbers and one side for even numbers (parity). Based on these criteria, the measured distance of each site from the beginning of the road which it accesses determines the locatable distance-based address for that site.
There are two primary methods for establishing the distance to each address site: 1) field measurement using a linear measuring device such as a fifth wheel, and 2) Geographic System Information (GIS) methods to calculate the distance along a digital arc that represents the centerline of the road network to be addressed.
Field measurement involves proceeding to the beginning of each road to be addressed, setting the measurement device to zero and then recording the distance to each site, the side-of-road and, if available, the resident name/address information. Typically, the information is immediately entered into a computer database or written on paper forms and entered at a later time. The process requires manipulation and manual recording of vast amounts of information. Numerous errors are generally introduced in the measured distance, the side-of-road, and the existing address information. As a tabular database, visual inspection is the only means for review.
GIS calculation requires development of a road centerline (C/L) spatial database and capture of the coordinates of each building and/or access point. There are many GIS techniques for determining the distance along each road arc to a specified point along that arc. Typically, the distance is manually entered as an attribute for each address point, or a GIS procedure is used to measure and record the distance as an attribute without manual intervention. Assignment of side-of-road has been done manually. Capture of site coordinates utilizes rectified aerial photographs or with field operated global positioning systems (GPS).
Regardless of measurement technique, an essential part of any E-911 system is collecting current resident name and address data. This data is used to notify occupants of their E-911 address and must be stored as an attribute with the proper site point. Failure to accurately assign this data to the proper site would cause the wrong occupant to be notified of a newly assigned address.
For geographic areas that have addressing, manual inspection has been the methodology for insuring that sites have been properly addressed. Unfortunately, errors in parity and increment are extremely common. Geo-coding is the process of attributing each road segment between intersecting roads in a GIS road C/L data layer with the high and low address number for sites on each side of the road. This process is used for forming a required data layer for PSAPs having a map display. The data provides the basis for locating any address. However, manual entry of such information is prone to error. In addition, the updating of geo-coding is prone to error or, since automation of this task has not been fully realized, is often neglected.
GIS data development and address conversion must be validated with multiple, independent sources of tabular and spatial data. Quality assurance of captured data needs to be designed into the development plan. Unfortunately, it is not sufficient to make use of a plan that merely captures feature coordinates and a set of attributes without a plan for assuring its accuracy. Quality assurance by inspection is not a sufficiently reliable method of providing error-free data. Complete inspection requires quality control personnel to plot, inspect, and identify (if possible) errors to be reworked. Once reworked, it must again pass through quality control and be completely re-inspected (now 200% inspection) and passed or returned for additional rework and continued looping until all observed errors have been eliminated. This is time-consuming and will likely never ensure complete accuracy. Accordingly, this method is inadequate for E-911 data development.
Even after addresses have been developed and entered into the ALI/DBMS, this data, including the MSAG, must be properly maintained. Since the MSAG is a table of addresses having no spatial component, erroneous data is frequently entered without any type of spatial system to audit the validity of the data. Errors (discrepancies) are detected only at the time of an emergency call. These errors cause inappropriate routing and may add significant delay to the response of an emergency call. Errors include wrong address ranges, wrong ESNs, multiple entries of a street with different spellings, and inaccurate community names.
Database standards for 9-1-1 systems currently include a field for an x-y coordinate for each TN record in the ALI/DBMS. The plan has been to include the x-y coordinate stored in the ALI/DBMS with the other data downloaded to PSAP 18. A map display could use this location information to display the location of that TN on a map. These data fields have never been used as a result of the difficulty in properly maintaining this information. As telephone numbers are commonly transferred from one permanent address to another, it is not a good plan to store x-y coordinates in the ALI/DBMS with the TN. If a TN record misses being updated, an erroneous x-y coordinate would remain stored with the TN. As it is extremely difficult to find such errors, E-911 systems relying on this requirement would be unreliable and could prove hazardous.
The spatial nature of the MSAG is currently not considered during updating procedures. An MSAG is currently updated using traditional tabular techniques that are disassociated from GIS map data and geo-coding. Even when update of both tabular and GIS data is done, it is currently performed as two discrete and independent steps.
Wireless calls from cellular telephones and other radio-wave based devices, which have no fixed address, cannot be automatically routed using address-based E-911 system 30. When a wireless subscriber initiates an emergency telephone call, the billing address information, even if retrieved by the PSAP, is of no value in determining the present location of that mobile subscriber. Although there are various technologies currently being developed that will allow a wireless carrier to report the location (x-y coordinate) of the mobile subscriber to the PSAP, routing of coordinate-based 9-1-1 calls to the proper PSAP has yet to be accomplished. To provide the same level of service for a wireless call as is currently provided by wireline calls, this x-y coordinate needs to have automatic determination of the ESN for every location.
The Federal Communications Commission (FCC) has mandated that the cell and sector of the tower receiving a call from a cellular telephone be provided with the CPN for any PSAP ready to receive this information. In addition, the FCC has mandated that by 2001 wireless carriers shall have the capability of providing an x-y coordinate of the calling party within 125-meters of their location at least 67% of the time. Thus, the nature of 9-1-1 call routing needs to evolve from fixed telephone locations to fixed and mobile telephone locations. In addition to the simple address-based MSAG, a spatial database is necessary to route a coordinate based emergency call. Maintenance of permanent and mobile phone data, including mobile cell tower and sector locations, needs to be simplified to ensure a more reliable and safer E-911 system.
The present invention generally relates to improvements in computer systems and application software for the development, validation and maintenance of addressing systems and the automated routing of emergency telephone calls from both fixed land sites and mobile wireless locations.
Accordingly, it is an object of the present invention to provide a method for automating the development, quality control and maintenance of both the tabular and spatial databases. The system utilizes road access zones (RAZs) that describe the geographic area adjacent to each segment of each named road that accesses the geographic area.
Accordingly, a first aspect of the invention is a method of forming RAZs from geographic data in vector form which includes a plurality of road names, address numbers, and road center lines. The method comprises the steps of first, assigning a number to each road name, then creating a roadname route system based on the plurality of road names and the address numbers, then creating a plurality of polygons, wherein each polygon is associated with a different road name number, and then finally overlaying the road center lines with the polygons so as to define a left side and a right side of each road center line.
A second aspect of the invention is a method of creating an ESZ data layer having emergency service numbers, from a an MSAG using RAZs each having associated attributes including a road name, a road center line and an emergency service number. The method comprises the steps of first linking the RAZs to the MSAG through the road names, and then creating a plurality of emergency service zones by combining the RAZs that have the same emergency service number.
A third aspect of the invention is an enhanced 9-1-1 system for providing emergency communication between a telephone having an associated telephone number, a calling party number, and a location, and one or more associated emergency service providers. The system comprises a mobile telephone switching office in radio wave communication with the telephone, and a public service answering point in electronic communication with the mobile telephone switching office and the one or more associated emergency service providers. The system also includes a location determination unit in electronic communication with at least one of the mobile telephone switching office and the public service answering point, for providing the location of the telephone. Further included is a router switch in electronic communication with the public service answering point. The router switch contains router software for distributing calls to an available call-taker in the public service answering point. The system also includes an emergency service zone GIS data layer (ESZ) in electronic communication with the router switch. The ESZ coverage defines the geographic area of service for each unique combination of law, fire, and EMS emergency service agencies. The ESZ provides information to the public service answering point as to the emergency service agencies providing service to every location within the 9-1-1 service area.